Panels and insulation systems of the general type involved herein are known. For example, see U.S. Pat. No. Re. 27,330 and U.S. Pat. No. 4,163,347. The panels are utilized to thermally insulate tanks and/or pipes but may be utilized for other structures. The panels disclosed in said patents are generally 4'.times.8' with the longer side edges being horizontally disposed. In said patents, and commercial embodiments thereof, banding overlies the joints between panels and constitutes the means for keeping the vertical seal between adjacent panels weather-tight. It is essential that the panels be permitted to expand and contract to the circumferential direction with temperature changes of the tank or other structure which is insulated.
The present invention is directed to a solution of the problem of how to make the joint between adjacent panels in systems of the type disclosed in said prior art patents more efficient while at the same time decreasing the cost of the system.